SPACECALC - Storage efficiency right from the start: file modeling and allocation:

If your installation is like most, there never seems to be as much DASD as you would like. Now you can get that extra storage without buying more hardware. You’ll make your operation more efficient in the process. Development and testing can be smoother and jobs can run faster, all thanks to SpaceCalc.

SpaceCalc can help data centers achieve efficient DASD utilization at allocation time, rather than recovering over-allocated space or re-blocking after the fact.

For programmers, SpaceCalc represents an alternative online allocation facility. SpaceCalc will determine a file’s DASD requirement before the online allocation is performed. Thus the over-allocation associated with users estimating their file’s DASD requirement when using ISPF 3.2 can be avoided.

For DASD managers, SpaceCalc represents the perfect tool to process allocations made on a written request basis. With the newest release, SpaceCalc will now optionally determine the DFSMS class in which the allocation will be made. Requests for allocations can be performed in bytes, kilobytes, and megabytes for easy DFSMS file allocations.